JPH02145401A - Reformer - Google Patents

Abstract

PURPOSE:To enable to produce H2 and Co from a hydrocarbon readily and in a high heat efficiency by forming a heat flow rotating along the inside of a reaction tube with combustion gases blown off from burners disposed toward the tangential lines of a circumference. CONSTITUTION:A doubly cylindrical reaction tube 3b filled with a reforming catalyst 5 is disposed in a reformer. Plural fuel-jetting nozzles 8a-8d are disposed circumferentially at equal intervals at positions near the axially lower (or upper) end of the reaction tube 3b and inside the reaction tube 3b and further burners 7a-7d whose nozzles are directed toward the respective tangential lines of the circumference are disposed. Gases to be reformed are supplied into the reaction tube 3b from the end side thereof on which the burners are disposed. A heated gas flow rotated along the inside of the reaction tube 3b is formed with a combustion gas jetted from the nozzles on the combustion of a fuel. Thereby, a space is formed at the central position of the reformer and can be utilized for the pre-heating, etc., of the gases used for the reformation. Since the combustion gas gives a large amount of heat to the inlet portion of the reaction tube 3b for the mixed gases to be reformed, the reformation of the gases to be reformed can be realized in a high efficiency of heat.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a reformer that produces hydrogen and carbon monoxide using hydrocarbons as raw materials.

(Prior art) A reformer that produces hydrogen and carbon monoxide from hydrocarbons is known, and is used, for example, as a main component of a fuel cell or as a device for producing atmospheric gas for carburizing. It is being

Taking fuel cells as an example, fuel cells have been actively developed in recent years with the aim of putting them into practical use as power generating devices with high power generation efficiency that directly convert the chemical energy of raw material gas into electrical energy. In particular, cogeneration type on-site fuel cells, which are placed near demand points and utilize heat generated at the same time as electricity, are attracting attention as an effective use of fuel cells and are being developed.

On-site fuel cells are required to be smaller and more efficient, and many proposals and developments have been made to make the reformer, which is one of the main components of a fuel cell, smaller. . A reformer produces hydrogen-rich reformed gas needed by the battery by reforming raw material gas such as city gas at high temperatures.This reforming reaction is an endothermic reaction, and how The key to making the reformer smaller and more efficient is how efficiently heat is transferred to the reforming catalyst layer inside the reaction tube, where the mixture of raw material gas and steam flows.

As an example of a reformer that has been proposed in the past,
No. 1608 has a burner in the center.

A reformer is disclosed in which annular first and second reforming catalyst layers are arranged concentrically around the reformer, and the outer second reforming catalyst layer converts the raw material gas into combustion gas and the raw material gas itself. After preliminary reforming, the reformed gas is heated by combustion gas in the inner first reforming catalyst layer to obtain reformed gas.

As typified by this reformer, in almost all conventional reformers, the burner is placed in the center of the reformer from the perspective of effective heat utilization, so the space in the center of the reformer is occupied by the burner. If you try to preheat the air used for combustion in the burner or the steam used for reforming by mixing with the raw material gas, you have no choice but to preheat it further outside the reforming catalyst-filled reaction tube placed around the burner. , there is a problem that the entire reformer becomes large.

In addition, in a type of reformer where the burner is placed in the center, the combustion gas from the burner flows in the axial direction of the burner, so heat transfer is insufficient at the inlet of the reaction tube where heat absorption is most required. There is an aspect of the reforming reaction, which is an endothermic reaction, that is unsatisfactory.

Furthermore, when considering the reformer used in fuel cells, when starting up a fuel cell, it is necessary to use natural gas (
It is common practice to combust raw material gas such as methane (which has methane as its main component), and then, after a certain period of time, to combust the remaining hydrogen discharged from the combustion battery. When it comes to burning two different fuels.

The nozzle in the center of the burner needs to have a double structure. However, a reformer of the type in which the burner is located in the center has a problem in that the nozzle structure in the center of the burner becomes complicated.

(Objects and Structure of the Invention) The present invention has been made in view of the above points, and has a nozzle structure that allows as much space as possible in the center of the reformer, increases heat transfer at the inlet of the reaction tube, and burns different fuels. The purpose is to provide a relatively simple reformer,
To achieve this objective, an annular reaction tube filled with a reforming catalyst is arranged inside the reformer, and a plurality of fuel injections are arranged inside the reaction tube and near the axially upper or lower end of the reaction tube. A burner is arranged in which nozzles are arranged at equal intervals on the circumference and each nozzle is oriented in the tangential direction of the circumference, and the gas to be reformed is supplied to the reaction tube from the end side where the burner is arranged. However, the combustion gas ejected from the nozzle during combustion in the burner forms a heat flow that swirls along the inside of the reaction tube.

(Example) The present invention will be explained below based on the drawings.

FIG. 1 is a sectional view showing the structure of a reformer developed for use in fuel cells as an embodiment of the reformer according to the present invention.

The reformer has double annular tubes 3a and 3b arranged inside a heat insulating container l made of a metal frame filled with heat insulating material, and a burner 4 (internal (shown with a portion cut away to make it visible).

Of the double annular pipes 3a and 3b arranged in the heat insulating container l, the outer annular pipe 3a mixes the raw material gas such as natural gas to be reformed and water vapor supplied from above the container l. This is a preheating tube for preheating gas, and the inner annular tube 3b is filled with a reforming catalyst 5, and the mixed gas preheated in the preheating tube 3a is subjected to a reaction of being reformed by the reforming catalyst 5. It's a tube. These preheating tube 3a and reaction tube 3b penetrate the earthen wall 1a of the heat insulating container l and extend upward.

A cylindrical partition wall 6 is attached to a horizontal flange 13a of a cylinder 13, which will be described later, and is provided between the preheating tube 3a and the reaction tube 3b, with a portion of the lower end remaining.

Next, as shown in FIGS. 2 and 3, the burner 4 is cut out at four locations A, B, C, and D at equal intervals on the circumferential surface of a cylindrical bousing 4b with a flange 4a. There are nozzles 7a, 7b, 7 for spouting combustion gas for startup, respectively.
c, 7d are arranged tangentially, and these nozzles 7a.

Four nozzles 8a, 8b, 8c, and 8d for ejecting combustion gas for operation are arranged in the radial direction at intermediate positions between the nozzles 7b, 7c, and 7d. startup combustion gas jetting nozzle 7a;
Air blowout openings 9a, 9b are provided around 7b, 7c, and 7d.
, 9c, and 9d are formed concentrically. Conduit pipes 10a, 10b, 10c, and 10d are connected to the startup combustion gas jetting nozzles 7a, 7b, 7c, and 7d, respectively, and the driving combustion gas jetting nozzles 8a, 8b, and 8c.

8d have conduits 11a, llb, and llc, respectively.

lid is connected.

Above the burner 4, a triple-structured conduit 12 for guiding fuel and combustion air to the burner 4 extends through the upper wall 1a of the heat-insulating container l, and a triple-structured conduit 10 is connected to the outermost pipe 12a. , an intermediate tube 12b, and an innermost tube 12c. The innermost tube 12c is supplied with a starting fuel gas, such as natural gas, which is supplied to the conduits 10a, 10b.

10c, lOd via nozzles 7a, 7b.

7c and 7d, and is ejected from these nozzles in the direction in which the burners are connected. An operating fuel gas, such as hydrogen gas discharged from the anode of the fuel cell, is supplied between the innermost conduit 12c and the middle conduit 12b, and this gas is supplied to the conduit 11a.

Nozzle 8a via 11b, llc, lid.

8b, 8c, and 8d, and is ejected from these nozzles in the radial direction of the burner. Combustion air is also supplied between the middle tube 12b and the outermost tube 12a, and this air is discharged into the housing 4b of the burner 4 and is fed into the opening 9a.
, 9b, 9c, and 9d to the outside in a tangential direction.

On the other hand, in the upper space of the burner 4, a ceramic cylinder 13 is attached to a flange 4 provided at the upper part of the burner housing 4b so as to surround the triple-structure conduit 12 described above.
The tube wall 14, which is also cylindrical, is provided halfway between the cylinder 13 and the outermost tube 12a.

Next, the generation of reformed gas by the reformer having the above structure will be explained in relation to the operation of the fuel cell.

When starting up the fuel cell, for example, natural gas is supplied as a starting fuel gas to the innermost tube 12c of the conduit 12, and combustion air is supplied between the intermediate tube 12b and the outermost tube 12a. As a result, natural gas flows through conduits 10a-1
0d and is ejected from nozzles 7a to 7d.

On the other hand, since the combustion air is ejected from the surrounding openings 9a to 9d, when ignited, the natural gas is combusted at the tips of the nozzles 7a to 7d to form a flame. Nozzle 7a
~7d are oriented in a tangential direction on the circumference of the cylindrical housing 4b, so the direction of the flame is also tangential. 3b is arranged to surround the burner 4, the combustion gas ejected from the nozzles 7a to 7d flows through the reaction tube 3.
It hits the lower inner wall of b and flows along the inner wall,
A clockwise swirling heat flow is formed around the burner 4 as shown by the arrow in FIG.

The combustion gas rises while swirling along the inner wall of the reaction tube 3b, and during this time it also gives heat to the reforming catalyst 5. The combustion gas is passed through the horizontal brim 13a at the top of the cylinder 13 at the top of the reformer.
When the water hits this, it flows in the opposite direction (downward), and when it reaches the bottom end, it changes its direction upward at the partition wall 6, rises, and flows in the direction of the arrow. Beyond that, the combustion gas flows downward through the gap between the cylinder wall 14 and the ceramic cylinder 13, and near the O of the burner 4, it now flows upward through the gap between the cylinder wall 14 and the outermost tube 12a of the conduit 12, and is reformed. It is discharged outside the container.

When a mixed gas of natural gas and steam, which is a raw material gas, is fed into the preheating tube 3a, the mixed gas is preheated by combustion gas while passing through the preheating tube 3a, and enters the reaction tube 3b. Since the reforming catalyst 5 filled in the reaction tube 3b is heated by the combustion gas from the burner 4, the mixed gas entering the reaction tube 3b is reformed by the reforming catalyst 5 while passing through the reaction tube 3b. The hydrogen-rich reformed gas is output from the outlet above the reaction tube 3b and sent to a fuel cell (not shown).

In this case, the swirling flow of high-temperature combustion gas formed by the burner 4 first hits the lower part of the reaction tube 3b and gives a large amount of heat there, so that the mixed gas entering the reaction tube 3b from the lower part of the reaction tube 3b In this part, the gas is reformed by the action of the catalyst that has absorbed sufficient heat. Furthermore, the combustion gas rises along the reaction tube 3b while swirling, but during this time it flows in parallel with the mixed gas flowing upward in the reaction tube 3b, and after changing its flow downward, the mixed gas flows through the preheating tube 3a. This creates a countercurrent flow, allowing for efficient heat transfer.

On the other hand, the combustion gas rises above the burner 4 inside the cylindrical wall 14 in the opposite direction to the combustion air flowing downward between the outermost pipe 12a and the middle pipe 12b of the conduit 12. Preheat.

Hydrogen-rich reformed gas obtained from the reformer started in this way is supplied to the fuel cell and used for power generation by the fuel cell.

When a predetermined period of time has elapsed after startup, the innermost pipe 1 of the conduits 12 uses hydrogen discharged from the fuel cell as an operating fuel gas.
2c and the middle pipe 12, and also stops the natural gas that had been supplied to the innermost pipe 12c. As a result, the supplied hydrogen is ejected from the nozzles 8a-8d through the conduits 11a-lid, and has already been ejected from the openings 9a-8d.
Together with the combustion air being blown out from 9d, it is ignited and starts to burn due to the swirling heat flow that is being formed at that time, and since the combustion air is blown out in the tangential direction of the burner 4, the swirling continues as before. A heat flow is formed and a reforming action takes place in conjunction.

In the above embodiment, the burner was placed at the bottom of the reformer, and the preheating tube for combustion air was provided in the space formed above the burner. The space formed below may be used for preheating the combustion air. Further, the space formed above or below the burner may be used for preheating steam to be mixed with other gases, such as raw material gas, or may be used for other purposes. Further, the supply of fuel gas and combustion air to the burner is not limited to the axial direction as in the embodiment.

Furthermore, in the above embodiment, the flow directions of the mixed gas of raw material gas and steam and the combustion gas are parallel when viewed inside the reaction tube, and are reversed when viewed inside the preheating tube. Although this is preferable in order to obtain high thermal efficiency, it is not essential in the present invention.

Furthermore, it goes without saying that the reformer according to the present invention is suitable not only for use as a component of a fuel cell, but also for other uses.

(Effects of the Invention') As explained above, in the present invention, an annular reaction tube filled with a reforming catalyst is arranged inside the reformer, and the reaction tube is placed inside the reaction tube and at the upper end in the axial direction of the reaction tube. or near the bottom edge,
A burner is arranged in which a plurality of fuel injection nozzles are arranged at equal intervals on the circumference and each nozzle is oriented in the tangential direction of the circumference, and the reaction tube is heated from the end side where the burner is arranged. The structure is configured so that a heat flow swirling along the inside of the reaction tube is formed by the combustion gas ejected from the nozzle during combustion in the burner, so a space is created in the center of the reformer. This space can be used for preheating the gas required for reforming. Furthermore, since the combustion gas provides a large amount of heat to the inlet of the mixed gas to be reformed in the reaction tube, reforming with high thermal efficiency can be achieved. moreover,
When used with a fuel cell, the nozzle structure of the burner becomes simple, which makes the overall structure of the burner compact, and the reformer uses different fuels during startup and operation. Contributes to downsizing.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of a reformer according to the present invention, and FIG.
The figure is a perspective view of a burner used in a reformer according to the present invention;
FIG. 3 is a bottom view of the burner as seen from line 1--m in FIG. 1. l...insulation container, 3a...preheating tube, 3b...reaction tube, 4...burner, 4a...flange, 4 b-...
-Housing, 5-...Reforming catalyst, 7a-7d-...
Starting fuel injection burner, 8a to 8d... Operating fuel injection burner, 9a to 9d-opening, 10a to 10d,
lla~lld, 12-... Conduit patent applicant Tokyo Gas Co., Ltd. Agent Patent attorney Hiroo Suzuki

Claims (3)

[Claims] (1) An annular reaction tube filled with a reforming catalyst is arranged inside the reformer, and a plurality of fuel injection nozzles are arranged circumferentially inside the reaction tube and near the axially upper or lower end of the reaction tube. Burners are arranged at regular intervals and each nozzle is oriented in the tangential direction of the circumference, gas to be reformed is supplied to the reaction tube from the end side where the burners are arranged, and the burner combustion 1. A reformer characterized in that the combustion gas ejected from the nozzle forms a heat flow that swirls along the inside of the reaction tube. (2) The reformer according to claim 1, further comprising a nozzle for ejecting different fuels between two adjacent fuel ejecting nozzles of the burner. (3) The reformer according to claim 1 or 2, wherein a preheating tube for heating combustion air or reforming steam is disposed in a space formed above or below the burner inside the reaction tube. (4) Inside the reaction tube, the combustion gas ejected from the burner flows in parallel with the reformed gas flowing inside the reaction tube, and outside the reaction tube, the combustion gas flows in the opposite direction to the reformed gas. 4. The reformer according to claim 1, wherein flow paths for reformed gas and combustion gas are formed.